Core-First Synthesis of Three-, Four-, and Six-Armed Star-Shaped Poly(methyl methacrylate)s by Group Transfer Polymerization Using Phosphazene Base

Abstract

The core-first synthesis of three-, four-, and six-armed star-shaped poly(methyl methacrylate)s (PMMAs) with predicted molecular weights and narrow molecular weight distributions (M w /M n s) was carried out by the t-Bu-P 4 -catalyzed group transfer polymerization (GTP) of methyl methacrylate (MMA) using the newly designed silyl enolates, such as 1,1,and bis{2,2,2-tris[2-methyl-1-(trimethylsilyloxy)prop-1-enyloxy]ethyl}ether (O-(C(MTS) 3 ) 2 ), respectively. The absolute molecular weight (M w (MALS)) of the obtained polymers proportionally increased with the increasing [MMA] 0 /[initiator] 0 ratio, and the highest molecular weight was ca. 132 kg mol À1 . Characterizations for the star-shaped PMMAs were conducted by cleavage and intrinsic viscosity [η] experiments. Cleavage experiments of the star-shaped PMMAs provided the evidence for homogeneous growth of the each arm in the t-Bu-P 4 -catalyzed GTP.The number of arm determined from the shrinking factors (g 0 ) of [η] also supported the successful syntheses of the star-shaped polymers by the present core-first method. The versatility of this core-first method toward other methacrylic monomers was confirmed by the t-Bu-P 4 -catalyzed GTPs of allyl methacrylate (AMA), stearyl methacrylate (SMA), and 2-(dimethylamino)ethyl methacrylate (DMAEMA) using C(MTS) 4 as an initiator leading to well-defined star-shaped polymers.

B(C6F5)3-catalyzed group transfer polymerization of alkyl methacrylates with dimethylphenylsilane through in situ formation of silyl ketene acetal by B(C6F5)3-catalyzed 1,4-hydrosilylation of methacrylate monomer

“…5 ,4Λ 5 -catenadi(phosphazene), [14][15][16] and tris(2,4,6-trimethoxyphenyl)phosphine, 17 have been used for the controlled/living GTPs of methyl methacrylate (MMA) and tertbutyl acrylate. In addition, acid organocatalysts, such as triphenylmethyl tetrakis(pentafluorophenyl)borane, [18][19][20][21] (R)-3,3'-bis[3,5-bis(trifluoromethyl)phenyl]-1,1'-binaphthyl-2,2'-disulfonimide, 22 trifluoromethanesulfonimide, [23][24][25][26] N-(trimethylsilyl)triflylimide, 27,28 and 1-[bis(trifluoromethanesulfonyl)methyl]-2,3,4,5,6-pentafluorobenzene, 25,26 were suitable for the controlled/living unstable SKA.…”

Star‐shaped POSS–methacrylate copolymers with phenyl–triazole as terminal groups, synthesis, and the pyrolysis analysis

“…17 For the synthesis of these star-shaped polymers, the "core-first" method is often used, where an active multifunctional POSS core works as the initiator for polymer chain growth. [18][19][20][21][22][23][24] Chen et al 25 synthesized a series of star-like light-emitting materials by hydrosilylation of the POSS, and obtained polymers exhibited enhanced T d temperatures.…”

Group Transfer Polymerization

“…Subsequently, oxyanions and bioxyanions were developed, which could be handled more easily and used to perform GTP at temperatures above the ambient temperature. Table 1 summarizes several examples of systems used for GTP along with these The newest generation of GTP catalysts includes NHCs (53-56,61), Brønsted phosphazene bases (63)(64)(65), and strong Brønsted acids (57,66,67). These new catalytic systems have broadened the scope of GTP by allowing the controlled polymerization of new monomer types, including methacrylonitrile and N,N-dimethylacrylamide.…”